There are not a few people who have ever had that strange feeling of having lived exactly the same situation before, as if we were reliving a scene that has already happened: “I have already lived this”. This phenomenon, known as déjà vu, is the phenomenon that you have experienced something before, while knowing that you have not.
For example: you visit a friend’s house and you have the feeling that you have been there before, but it is impossible, because it is the first time you visit the city. Still the feeling can be so intense and so real it’s scary. Experts estimate that about two out of three people have experienced it at some point. In fact, the phenomenon has been intriguing philosophers, neurologists, and writers for decades. Now the first study to use virtual reality to investigate it in a lab is helping to demystify what it really is. Let’s see how it works.
The French term déjà vu, which translates into English as “already seen”, was first studied by philosopher and psychic researcher Émile Boirac in 1876 but people had obviously experienced it long before it had a name. Each thinker gave it his own meaning: Sigmund Freud saw in that sensation repressed desires. Carl Jung believed that this experience was related to the collective unconscious. Plato described something similar as evidence of past lives. And, of course, there is the modern idea of Hollywood, which says that it is simply the result of an error in the Matrix.
At the end of the 19th century, the theory that began to make the most sense in the society of the time was that it was a mental dysfunction or a type of brain problem. But the subject did not reach the laboratories until very recently, in an investigation that has gone from the paranormal to the scientific. Scientist Alan Brown decided to conduct a review of all the literature surrounding this phenomenon to date and determined that the most common trigger for déjà vu is a scene or placeand the next is a conversation.
Their work helped researchers such as cognitive psychologist Anne Cleary of Colorado State University and her colleagues carry out studies like the one we are dealing with today. Experiments that seek to see if spaces modeled in virtual reality can replicate the experience. They basically worked with an old hypothesis that suggested that déjà vu occurs when there is a spatial resemblance between a current scene and an unremembered scene in your memory. Psychologists called this the Gestalt familiarity hypothesis.
In the example that we mentioned before of your friend’s house, the cause could be that the scene designincluding the placement of furniture and particular objects within the space, which have the same design as a different scene you experienced in the past.
Something like the following image:
To investigate this idea in the lab, Clearly’s team used virtual reality to position people within scenes. That way they could manipulate environments people were in: some scenes shared the same spatial layout but were otherwise distinct from each other.
The study concluded that déjà vu most often occurred when new scenes were very similar to previously experienced scenes in terms of their spatial layout, but not similar enough for people to consciously recognize the resemblance. However, that does not mean that spatial resemblance is the only cause. Most likely, many factors can contribute to a scene or situation being simply familiar: the key to this matter.
Other past theories
Before this study, there were many theories about what happens in the brain during that experience. One was that déjà vu is just a memory problem: when you come across something similar and recognize the familiarity but just can’t remember it.
Another theory was that déjà vu is caused by a time mismatch or interruption in the continuous flow of processing. For example, imagine you were walking down the street and passed a new coffee shop. You took a look around the premises, but at that moment you received a call and looked away, so you didn’t register it completely. The information was processed at some level, but not 100%. When you look up and see the cafeteria, you have the strange feeling that you’ve seen it before, because you just saw it, even though you don’t have a memory of it.
Another theory is that déjà vu is caused by mini-seizures. It is known that the people with epilepsy They have frequent experiences of this kind. Although it is believed that it is possible that déjà vu in people without epilepsy is also caused by some type of seizure-like activity. The brain just misfires a little bit and that causes the phenomenon.
Image: Unsplash